Methods which determine network performance by determining not only the transit delay between nodes in a network but also the variance, or jitter, of such transit delays. A common node, usually a network management computer (NMC), sends out a signal to a first node of interest and measures the time before it receives an acknowledgment from the first node. The NMC then sends out a similar signal to a second node of interest and similarly measures the time required to receive an acknowledgment. Based on these two measurements, the transit delay between the first and second nodes can be calculated if the first node lies on the path between the NMC and the second node or vice versa. For a multiple node communications path, the total transit delay between any two nodes is the sum total of the transit delays between adjacent nodes lying on the path. In the case of meshed networks, where a path to a node may be ambiguous, additional measurement nodes strategically positioned in the network can be used such a way that the transit delay between any adjacent pair of nodes can be calculated unambiguously from at least one of these measurement nodes, i.e., the portion of the network being measured will be reduced to a hierarchical one with respect to at least one of the measurement nodes.
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2. A method as in claim 1 wherein at least one of the first and second nodes are directly connected to the common node.
3. A method as in claim 1 wherein at least one of the first and second nodes are indirectly connected to the common node.
4. A method of determining the quality of communications between two nodes in a network, the method comprising: a) measuring a transit delay between the two nodes at different times resulting in a plurality of transit delay measurements; b) calculating a jitter among the plurality of time delay measurements based on measuring a variance of the plurality of transit delay measurements; and c) determining if the jitter exceeds a predetermined threshold value.
6. A method as in claim 4 wherein the transit delay is measured between a start node and an end node in a hierarchical network using the following method: a) determining interim transit delays between adjacent nodes in a communications path between the start node and the end node; and b) calculating the total transit delay between the start node and the end node by adding up the interim transit delays.
7. A method as in claim 5 wherein the hierarchical network is a portion of a mesh network.
8. A method as in claim 7 wherein the hierarchical network is a portion of a mesh network.
9. A method as in claim 4 wherein step c) includes determining if at least one of the transit delay measurements exceeds a predetermined threshold value.
11. A method as in claim 10 wherein the two nodes are directly connected to each other.
12. A method as in claim 10 wherein the two nodes are indirectly connected to each other.
13. A method of determining a jitter between a plurality of transit delay measurements between two nodes, the method comprising: calculating the jitter based on J ( A , B ) = ∑ i = 1 M D ( A , B , i ) 2 ∑ i = 1 M D ( A , B , i ) where J(A,B) is the jitter between the plurality of transit delay measurements; D(A,B,i) is the i th transit delay measurement among the plurality of transit delay measurements; and M is the number of transit delay measurements.
14. A method as in claim 13 wherein the two nodes are directly connected to each other.
15. A method as in claim 13 wherein the two nodes are indirectly connected to each other.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
June 23, 2000
October 17, 2006
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